不同营养水平日粮对奶公牛直线育肥性能的影响

为了研究不同能量和蛋白质水平日粮对奶公牛直线育肥性能的影响。选择4~5月龄左右、平均体重为121 kg的奶公犊36头,随机分成两组,试验Ⅰ组(饲喂低营养水平日粮)、试验Ⅱ组(饲喂高营养水平日粮),每组18头。试验期440 d。整个育肥试验以12月龄划分为前期和后期2个阶段。结果表明,整个育肥期,试验Ⅱ组的平均日增重比试验Ⅰ组提高了5.83%(P>0.05),料重比降低了3.11%(P>0.05)。试验Ⅱ组的粗蛋白质、粗脂肪、中性洗涤纤维、酸性洗涤纤维、钙和磷的表观消化率较高,但是与试验Ⅰ组差异不显著(P>0.05)。试验Ⅱ组的谷草转氨酶、谷丙转氨酶、生长激素、甲状腺素含量比试验Ⅰ组显著提高了8.27%,13.85%,6.70% 和1.26%(P<0.05)。血清尿素氮含量降低了12.22%(P<0.01)。两个营养水平日粮对屠宰率、胴体产肉率和净肉率没有影响。随着营养水平的提高,pH、剪切力、蒸煮损失、失水率有下降的趋势,牛肉中的蛋白质和脂肪含量有上升的趋势,但差异不显著(P>0.05)。与试验Ⅰ组相比,试验Ⅱ组的pH、剪切力、蒸煮损失和失水率分别降低了2.34%,12.97%,18.30%和3.38%,牛肉中粗蛋白和粗脂肪含量分别提高了4.95%和8.55%。养殖效益试验Ⅱ组比试验Ⅰ组多收入0.98元/(日·头),全期效益试验Ⅱ组比试验Ⅰ组多收入431.20元/头。因此,提高日粮的营养水平,可以促进奶公牛的生长、改善肉品质和增加经济效益。

Nutrition effects on growth of Holstein bulls

The objective of this trial was to evaluate the effects of different dietary energy and protein levels on linear-fattening performance of Holstein bulls. Thirty six Holstein bulls (mean live weight 121 kg) aged 4-5 months were allocated into two equal groups; group I (low nutrition diet) and groupⅡ(high nutrition diet). The experimental period continued for 440 days. The average daily gain (ADG) of group Ⅱ was 5.83% higher (P>0.05) than that of group I, but the feed/gain ratio of group Ⅱ was 3.11% lower than that of group Ⅰ(P>0.05). There was no difference between group Ⅰ and Ⅱ in the apparent digestibility of crude protein, ether extract, neutral detergent fiber, acid detergent fiber, calcium and phosphorus. Glutamic-oxalacetic transaminase, glutamic-pyruvic transaminase, growth hormone and tetraiodothyronine in the blood of group Ⅱbulls were increased by 8.27%, 13.85%, 6.70% and 1.26% (P<0.05) compared with group I bulls, respectively. The amount of blood urea nitrogen was significantly decreased 12.22% (P<0.01). Nutrition level had no effect on the dressing percentage, carcass weight and net meat percentage. Compared with group I, pH, drop loss, shear force and dehydration rate of group Ⅱ were decreased by 2.34%, 12.97%, 18.30% and 3.38% at 72 h, respectively. The amount of crude protein and ether extract were increased by 4.95% and 8.55%. The economic advantage of group Ⅱ bulls was 0.98 yuan/(head·day) compared to group Ⅰ. The total benefit from group Ⅱbulls was 431.20 yuan/head. Increasing energy and protein levels in diets of young Holstien bulls promoted growth and meat quality and the economic outcomes.